Refrigerant mixture



Patented Feb. 18, 1936 2,031,087 REFRIGERANI' manna Glenn F. Zellhoefer, Bloomington, Ill.

No Drawing. Application March 20, 1933, Serial N0. 661,789

1 Claim. (01. 252-5) The present invention relates generally to refrigerant materials for automatic refrigerators, and particularly to the type of refrigerant ma terial for the so-called two-fluid machines, wherein there is a solvent material adapted to remain liquid throughout the operation of the refrigerator, and a refrigerant material adapted to have a liquid and a vapor phase in the cycles of operation, and adapted to be dissolved in the solvent.

Numerous refrigerants and numerous solvents are known and numerous combinations of these are known.

The present invention is directed to a new solvent material and to the combination thereof with well-known refrigerant material,

One object of the invention is the use of dichlor benzol as a solvent for a refrigerant.

Another object of the invention is the use of dichlor benzol and methyl chloride in combina-= tion.

An example of an apparatus in which the new materials have been successfully employed is described in my copending application Serial No. 651,306 filed January 12, 1933.

Briefly described, the apparatus specifically re= ferred to comprises a still in which a mixture of solvent and refrigerant is heated to vaporize the refrigerant from the "solution, a condenser wherein the vapor is condensed to a liquid state, an evaporator wherein the liquid is vaporized at reduced pressure, such evaporator helps the effective cooling means, such as coils, in the apps ratus, and an absorber in which vapors containing added heat units are again dissolved in the solvent. Suitable heat exchanging and circu lation means are included, and automatic con-= trols may be provided.

The particular characteristics of such machines are that the still operates at temperatures .well

above normal temperatures against which the refrigeration acts, such for example, at 210 I". to 250 F'.; and that the cooling unit operates at temperatures much lower than normal, such as from 5 F. to 40 F. Various parts of the appa ratus differ in the prevailing pressures as well as temperatures and both pressure and temperature determine the physical state of the free refrigerant, whether gaseous or liquid and determine the solubility relations between the refrigerant and the solvent. It is therefore very important that the solvent and the. refrigerant be physically adapted for use as individual materials in oertain places and for certain functions, and that they be mutually adapted for certain functions not essential to refrigeration, but pertinent to practical usage control or limit the choice of solvent or refrigerant, such as odor, viscosity, heat capacity, boiling point, freezing point, volatility, chemical stability, reactivity, corrosive action, in-

ilammability, toxicity, etc.

In the following description the particular ad? vantages and merits oi'methyl chloride and of dichlor benzol and of their combination will liecome apparent as they are discussed with rela tion to these various important commercial factors.

Dichlor benzol Throughout this description the material may bination thereof. All forms boil at approximately 347 F. at atmospheric pressure which is far above the operating temperatures ordinarily contemplated. Hence thevolatility at the operating telnperatures is much less than with solvents having a lower hoilingpoint.v This is important in limfiting the amount of solvent which vaporizes with when they are in combination. Other qualities the refrigerant and accompanies it in its journey through the rectifier means.

The ortho and meta types are liquid at all tem peratures normally encountered in apparatus, and whatever small amount gets into the cooling means remains liquid and does not clog the apparatus. However, the para type freezes at about l2? F. This material might easily freeze solid in the cooling means or in some other part of the ap ratus where temperatures lower than about 127 F. are encountered. The presence oi refrigerant material with the wandering quantity of solvent may entirely prevent such solidifica tion, or may lower the effective freezing point,

where solidification may occur. Hence there is a remote but not eliminated possibility of clogging where the para type is predominating. Common cial grades of dichlor benzol contain varying quantitiesof the three types, but the predominance of the ortho and meta types overcomes the tendency of the para portion to freeze out. The

preferred form is the ortho type free from para type, although the commercial mixtures are entirely satisfactory for ordinary conditions of op= eration. v

For practical and mechanical considerations it is advantageous that the dichlor benzols are not corrosive towards iron, brass, copper, and bronze, and are inert of themselves, and to such metals, in the presence of air and water. Consequently, cast iron parts and flexible copper tubing may be employed in apparatus designed for use with them.

Methyl chloride This material is a gas or vapor at ordinary temperatures, and is subject to liquefaction by increased pressure and by lowered temperature. It is highly soluble in the dichlor benzol. Its refrigerant qualities apart from the dichlor benzol are well known. It is essentially odorless, and only slightly toxic. It is non-corrosive towards iron, brass, copper and bronze, and non-reactive with dichlor benzol. It is diflicultly inflammable.

Combination of dichlor. benzol and methyl chloride The dichlor benzols have a high solvent capacity for methyl chloride.

Apparatus of the two-fluid type may have a rectifier unit which treats the vapors from the still to remove solvent therefrom and return it to 6 to 28 pounds per square inch. These figures are merely exemplary of the range of pressure change and are not by any means to be considered as limits. The properties of the refrigerant, as related to the solvent, permit circulation through the cooling unit of a large amount of refrigerant per unit weight of solvent.

It is well known that there are other common refrigerants generally similar to and useful like methyl chloride, and that they can be used like methyl chloride in a variety of solvents. Because diohlor benzol has very specific advantages and properties in combination with methyl chloride, it will offer the same order of advantage with other refrigerants which have the same order of difference in properties or with mixtures of suitable refrigerant material. The specific solubility relations for refrigerant material, other than methyl chloride, may vary somewhat with corresponding changes in thermal eiliciency. Accordingly the present invention contemplates dichlor benzol as a new solvent, and the specific combination of methyl chloride and dichlor benzol. The proportions in which the solvent and refrigerant are used will, of course, depend entirely upon the type of apparatus employed, and also upon the particular design.

.While I prefer ortho or meta dichlor benzol, it is to be understood that whatever form or forms the dichlorbenzol has, the refrigerant mixture consists only of such material as the solvent, and

a suitable refrigerant material, preferably a single substance such as methyl chloride. It is further to be understood that if the materials are adulterated by the substitution of other solvent or refrigerant material in such a manner as to retain the substantial benefits and advantages of the unadulterated combination, then the adulterated composition is intended to fall withinthe scope of the appended claims.

What I claim is:

A refrigerant mixture for the absorption type of refrigeration apparatus consisting of normally liquid dichlor benzol as a solvent, and methyl chloride as a refrigerant.

GLENN F. ZELLHOEFER. 

